Hello,
We have an installation of Business Central 2020 Wave 1 with Cumulative update 17 on premises.
We are trying to export a company from the live database and import it in a test database.
To export a file containing the company we use the Export Data to a file functionality:

We get a message that data was exported successfully and a file TEST with a size of 52909 KB is created.
Then we try to import this file from Import from a data file by pressing the assist edit button and selecting the file:

Then we get the following error:
"The file could not be uploaded because it was too large. The maximum file size that can be uploaded is 350 MB."
Why occurs this error when the file size is only 53 MB?
How to export and import a company successfully?